Plunger and plunger assembly for a cartridge, system for storing a substance, and method of filing and sealing a substance in a delivery system

ABSTRACT

The present invention is directed to a plunger, a plunger assembly, and a system for storing a substance or substances, preferably flowable substances, and a method of filling and sealing a substance in a storing system. In particular, the present invention provides for substantially air-free filling and storing of substances in a delivery system.

FIELD OF THE INVENTION

The present invention is directed to a plunger, a plunger assembly, anda system for storing a substance or substances, preferably flowablesubstances, and a method of filling and sealing a substance in adelivery system. In particular, the present invention provides forsubstantially air-free filling and storing of substances in a deliverysystem.

BACKGROUND OF THE INVENTION

A common difficulty encountered during the manufacturing of standarddelivery systems is to provide encapsulation of the stored substancewithout voids or air bubbles. A standard process to avoid trapping airin a storage system or delivery system during assembly of the plunger ofthe system is to assemble the system under vacuum. However, a totalabsence of air cannot be achieved, so there will be a small amount ofremaining air in the storage or delivery system. Furthermore, the use ofa vacuum can also cause evaporation of the ingredients of the substance.The evaporation of ingredients may have a serious impact on the storedsubstance if the filling volume is very small, such as 1 ml or less, andif precise dosing is important, as with pharmaceutical products.

Another conventional process for filling a delivery system is to do sofrom the front end of the dispenser, which is the end through which thestored substance is dispensed. The plunger is thereby pushed backwardsduring filling. However, this process is limited to systems that allowfilling from the front end.

U.S. Pat. No. 5,178,305 relates to a dispensing cartridge with a storagecylinder and a dispensing piston whose bottom surface facing thecartridge contents is progressively recessed towards an air evacuationbore. The evacuation bore is sealed by a closure.

WO 01/94028 relates to a ventilation device for a piston for acartridge, comprising a first piston part which rests sealingly againstthe cartridge wall and a second piston part, which forms a valvetogether with the first piston part. Said valve opens when a pressure isexerted on the rear side of the piston so that the air that is trappedbetween the filling composition and the piston can escape. According tothe invention, a filter section is provided in front of the valve,between the two piston parts, as seen from the flow path of the airthrough the valve. This filter section has at least one narrow channelwhich forms a penetration barrier for the filling mass and ensures thatthe valve remains dry and free of dirt.

Further reference is made to EP-A-0 344 491, EP-A-0 463 991, FR-A-2 626248, EP-A-0 497 739, and U.S. Pat. No. 4,951,848.

SUMMARY OF THE INVENTION

According to a first aspect, the present invention provides a plungerfor a cartridge. The plunger has a first end and an opposite second end.The plunger comprises a passageway which extends between the first andsecond ends. The plunger comprises at least one constriction that isarranged in the passageway between the first end and the second end. Thediameter of the constriction is smaller than the smallest diameter of aplug that is movably insertable into the passageway.

The diameter of the constriction is preferably smaller than the diameterof the plug, at least in the area where the constriction seals with theplug. Furthermore, the diameter of the passageway of the plunger ispreferably in at least one location other than at the constrictionlarger than the largest diameter of the plug. This provides that theconstriction of the plunger seals with a plug that is movably insertableinto the passageway of the plunger. Trapped air in the cartridge canescape through the gap between the wall of the passageway and theinserted plug until the seal is established between the constriction andthe plug. It is preferred that the cartridge is then substantially freeof air. According to the present invention, substantially free of air isdefined as being free of air to the point where any remaining air doesnot interfere with the purpose or effect of the material beingdispensed.

According to a preferred embodiment, the constriction of the plungerforms a sealing lip that forms the seal with the plug. The sealing lip,the plug, or both are preferably deformable. Thus, once the plug isinserted into the passageway and reaches the sealing lip, the plugdeflects the sealing lip (or the sealing lip deflects the plug, or eachof them deflects), and the sealing lip is biased against the plug.

The present invention also encompasses that the inner surface of theplunger at the first end of the plunger is angled backwardly towards thepassageway. In other words, the first end surface of the plunger isinwardly tapered towards the passageway, or progressively recessedtowards the passageway. This assists in guiding trapped air along thefirst end surface to the passageway once the plunger is inserted andmoved toward the substance in the cartridge.

According to a preferred embodiment, the backwardly-angled first endsurface of the plunger terminates at the constriction. Alternatively,the constriction is set back in the passageway with respect to thebackwardly-angled first end surface of the plunger.

According to a second aspect of the present invention, a plunger for acartridge is provided. The plunger has a first end and an oppositesecond end, and a passageway that extends between the first and secondends. The passageway comprises a deformable first sealing lip thatprojects into the passageway.

As described with respect to the first aspect of the present invention,the first end surface of the plunger of the second aspect is preferablyangled backwardly towards the passageway, and more preferably terminatesin the deformable first sealing lip.

The deformable sealing lip is preferably deformable by a plug that isinsertable into the passageway from the second end of the plunger andmovable in the passageway. More preferably, the first sealing lip isdeformable by the plug towards the first end of the plunger. Thedeformable first sealing lip and the inserted plug form a seal.Alternatively, the first sealing lip is not deformable but rigid, andthe plug is deformable by the rigid lip.

Prior to the insertion of a plug, the surface of the first sealing lipis preferably angled or canted towards the passageway. More preferably,the first sealing lip comprises an edge.

The smallest diameter of the passageway of the plunger of the secondaspect is preferably smaller at the first sealing lip than the smallestdiameter of the plug.

It is preferred according to the first and second aspect of the presentinvention that the outer diameter of the plunger increases towards theedge of the plunger at its first end. Thus, the plunger comprises afirst part having a substantially constant outer diameter, and a secondpart having a diameter that increases from the diameter of the firstpart towards the first end of the plunger. Preferably, the edge at thefirst end of the plunger is formed as a second sealing lip for sealingagainst an outside wall, for example of the cartridge.

The plunger of the first or second aspect is preferably cylindrical inshape.

According to a third aspect, the present invention provides a plungerassembly for a cartridge. The plunger assembly comprises a plunger witha first end and an opposite second end, and with a passageway extendingbetween the first and second ends. The plunger assembly furthercomprises a plug that is insertable into the passageway. The plungerassembly also comprises at least one constriction within the passagewaybetween the first end and the second end of the passageway/plunger. Thediameter of the constriction is smaller than the diameter of the plug,at least in the area where the constriction seals with the plug. Theconstriction preferably forms a sealing lip for forming a seal with theplug. More preferably, the sealing lip is deformable. Alternatively, thesealing lip is not deformable but rigid, and the plug is deformable bythe rigid lip It is also preferred at the plunger assembly according tothe third aspect of the present invention that the diameter of thepassageway in at least one location other than at the constriction islarger than the largest diameter of the plug.

A retention element may be provided for locking the plug with theplunger when being assembled. Preferably, the plug comprises a steppedconfiguration having a first diameter in the area where the constrictionseals with the plug, and a second larger diameter closer to the frontend of the plug. Thus, the plug is locked with the plunger against areverse movement once it is inserted into the passageway in that theconstriction abuts against the step. More preferably, the steppedconfiguration is provided in form of an indented ring into which theconstriction lip fits to lock the plug in place. It is further preferredthat locking of the plug happens before (e. g. short before) the plughas reached its end position while it is inserted into the passageway soas to provide the possibility to move the plug to its end position andto move it back to the lock position. Alternatively, the passagewayincludes an indented ring, and the plug includes a protruding ridge forlocking the plug with the plunger.

According to a fourth aspect, the present invention relates to a systemfor storing a substance. The system comprises a container having acompartment for storing the substance, and a plunger according to thepresent invention. The plunger is displaceable in the containercompartment. Furthermore, the system also comprises a plug that isdisplaceable in the passageway of the plunger. Preferably, thecompartment is a generally cylindrical compartment.

As described above, the plunger of the system for storing a substanceaccording to the invention comprises at least one constriction that isarranged in the passageway between the first end and the second end ofthe plunger. The diameter of the constriction is smaller than thesmallest diameter of the plug, at least in the area where theconstriction touches the plug. Furthermore, the diameter of the plug ispreferably smaller than the diameter of the passageway. More preferably,a space is formed between the wall of the passageway and the plug suchthat air trapped in the container compartment is allowed to escapethrough this space, and such that excess substance in the compartment isreceivable in this space when the plunger is moved in the compartment.Preferably, excess substance is stored in the space once the plug hasreached the first sealing lip of the plunger.

In the system for storing a substance according to the invention, theplunger preferably comprises a first end edge that is formed as a secondsealing lip for sealing against an outside wall. Preferably, the secondsealing lip abuts against the inner wall of the container compartment.

According to a preferred embodiment of the invention, the plug comprisesat its back end a flange. The diameter of the flange is preferably sizedto close the space at the second end of the plunger. Thus, the diameterof the flange corresponds to the inner diameter of the plungerpassageway at the second end of the plunger.

The container may also comprise a dispensing opening for dispensing thestored substance.

The stored substance is preferably a dental substance, for example, adental paste or fluid such as a resin modified glass ionomer fillingmaterial, composite filling material, modified composite material, etc.

According to a preferred embodiment of the present invention, thecontainer of the system comprises two or more compartments for storingdifferent substances. For each compartment, a plunger according to theinvention is preferably provided. The system also comprises furtherplugs being displaceable in the passageways of the plungers for theadditional compartments. In this case, the plugs are preferablyconnected to each other, for example by a connecting bar. Morepreferably, the plungers are connected to each other at their secondend. It is further preferred that the plungers are connected to eachother by a connecting bar that is integrally formed as one piece withthe plungers. The plugs may also be integrally formed as one piece withthe connecting bar. Preferably, a retention element is provided forlocking the plugs with the plunger when being assembled. It is furtherpreferred that locking of the plugs happens before (e.g. shortly before)the plugs have reached their end position while they are inserted intothe passageways so as to provide the possibility to move the plugs totheir end position and to move them back to the lock position.

According to a fifth aspect of the present invention, a method offilling and sealing a substance in a storing system is provided. Acontainer having a compartment for the substance is provided. Thecompartment is filled with the substance. A plunger according to theinvention is placed into the compartment. The plunger is advancedfurther towards the substance until the substance passes the firstsealing lip of the plunger, wherein air is able to escape into thepassageway. The plug is pushed into the passageway of the plunger untilthe first sealing lip is sealed against the plug.

Preferably, excess substance passing the first sealing lip is receivedin the space between the wall of the passageway and the plug. The plugand the first sealing lip preferably form a seal against the substancecontained in the compartment.

According to a further embodiment the seal is provided as separate partand assembled into the passageway of the plunger. The seal preferablyhas a triangular cross-sectional shape or a circular cross-sectionalshape (O-ring). The passageway of this embodiment preferably (but notnecessarily) has a stepped configuration, which means that thepassageway has a first diameter towards the front end of the plunger anda second diameter towards the back end of the plunger, wherein the firstdiameter is smaller then the second diameter. The seal is received inthe second diameter and abuts at the step between the first and seconddiameter, thus being fixed against displacement when the plug isinserted in the passageway. Preferably, the plug comprises acircumferential flange for pressing the seal against the step.

According to another further embodiment the seal is provided at thefront end of the plug rather than in the passageway. The seal ispreferably of a triangular cross-sectional shape and preferablydeformable, thus forming a flexible sealing lip. Preferably the diameterof the sealing lip is substantially larger than the diameter of thepassageway. The plug is preferably pre-assembled with the plunger in amanner that the back end of the plug is located in the passageway of theplunger and the sealing lip is located outside of the passageway.Preferably the sealing lip is located within the inwardly tapered areaat the front end of the plunger, wherein the sealing lip does not touchthe plunger, providing that the plug does not seal with the plunger atthis stage.

According to a further alternative embodiment of the present invention,a method of filling and sealing a substance in a storing system isprovided. A container having a compartment for the substance isprovided. The compartment is filled with the substance. A plungerassembly according to the second alternative embodiment is placed intothe compartment. The plunger assembly is advanced further towards thesubstance until the substance penetrates into the front end of thepassageway of the plunger, wherein air is able to escape between theplug and the passageway. The plug is pulled back towards the back end ofthe plunger until the sealing lip has moved into the passageway, thussealing with the plunger. Because of the larger diameter of the sealinglip and because the sealing lip is deformable the sealing lip deflectstowards a direction of the substance filled in the compartment when itis moved into the passageway.

The present invention provides various advantages. First, ventilation isprovided so that air contained in the compartment can escape while theplunger is inserted so that substantially no air is trapped in thecontainer. Furthermore, a good encapsulation of the material is achievedwhich is very important with respect to aging of the material. Anincreased sealing effect is provided by the present invention uponexpelling material (when the plunger is pushed forward), because boththe first and second seals increase contact force to their respectivecontact surface upon increase of pressure in the container compartment(upon expelling material). Furthermore, the plunger, the plungerassembly, and the system of the invention are easy to manufacture.

A further advantage of the plunger of the invention is that the systemcan be filled through the plunger so that the container-plunger assemblycan in fact be preassembled. In this case the plunger is placed in thecontainer, and this pre-assembly is placed in the filling machine forfilling the material through the passageway of the plunger into thecontainer. After filling, the container-plunger pre-assembly is closedby the plug. Preferably closing is done by the steps of inserting theplug into the passageway completely and moving it back by a shortdistance so as to relieve the pressure in the container.

A further advantage of the invention over conventional systems is thatit can compensate for unequal filling performance during manufacturing,to a considerable extent, because it allows to accommodate aconsiderable amount of substance in the passageway of the plunger so asto provide that the plunger can be moved to a predefined position wheninserted into the compartment while excess substance is displaced intothe passageway of the plunger.

The excess substance is encapsulated between the wall of the passagewayand the outer surface of the plug when the plug has been inserted intothe passageway.

This is furthermore of advantage in combination with a system comprisinga container having two or more compartments, because the plungers can beinserted into the container simultaneously to a predefined positionwhile excess substance from all compartments will be displaced into thepassageways of the plungers independently from one another.

All described embodiments of the invention may also be used with adelivery system that allows filling from the front end (e. g. fillingthrough the dispensing opening of the delivery system). In this case theplunger may be preassembled in the container. The container fills fromthe front end towards the back end, wherein the air escapes through thepassageway of the plunger. Filling is stopped when substance has passedthe sealing lip in the plunger. After filling, the container-plungerpre-assembly is closed by the plug at it back end. The front end may beclosed before or after closing of the back end.

Alternatively the plunger is not pre-assembled with the container duringfilling from the container front end. In this case the container isclosed after filling as described for the system not allowing fillingfrom the front end.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages will be apparent from the following description anddrawings of the preferred embodiments of the present invention:

FIG. 1 shows a plunger according to a preferred embodiment of theinvention;

FIG. 2 shows a plunger according to an alternative embodiment of theinvention;

FIG. 3 shows an exploded view of a plunger assembly for a cartridgeaccording to the present invention;

FIG. 4 shows an exploded view of a system for storing a substanceaccording to the present invention;

FIGS. 5A-5D show the method of filling and sealing a substance in astoring system (schematic views) according to the invention;

FIG. 6 shows a system for storing a substance according to analternative embodiment of the invention;

FIGS. 7A-7D show the method of filling and sealing a substance in astoring system (schematic views) according to FIG. 6;

FIG. 8 shows the system of FIG. 4 with a modified plug;

FIG. 9 shows the system of FIG. 6 with an additional retention element;

FIG. 10 shows a system for storing a substance according to a furtheralternative embodiment of the invention;

FIG. 11 shows a cross-sectional view of a container having twocompartments and a dispensing cannula;

FIG. 12 shows a perspective view of the container of FIG. 11;

FIGS. 13A-13B show a plunger assembly for a cartridge according to afurther embodiment of the invention; and

FIGS. 14A-14B show a plunger assembly for a cartridge according to afurther embodiment of the invention.

FIG. 1 shows a plunger 10 for a cartridge (not shown) according to afirst embodiment of the invention. Plunger 10 comprises a first end 11and an opposite second end 12. Plunger 10 also comprises a passageway 13that extends between the first end 11 and the second end 12. As shown inFIG. 1, the diameter D of passageway 13 is preferably constant along asubstantial length of the passageway 13. Plunger 10 according to thepresent invention also comprises a constriction 14 that is arranged inthe passageway 13 between the first end 11 and the second end 12.Diameter d of the constriction 14 is smaller than diameter D of thepassageway 13, and is also smaller than the smallest diameter of a plug(not shown in FIG. 1) that is insertable into the passageway. Theplunger-plug combination is described in more detail below.

As shown in FIG. 1, constriction 14 is preferably formed as a sealinglip. In the preferred embodiment shown in FIG. 1, the cross-sectionalshape of the sealing lip is substantially triangular. That is, thesealing lip comprises angled surfaces that preferably terminate in anedge 15. Other sealing lips, surfaces, or arrangements may also be used,such as sealing bulges, o-rings, flat sealing collars of a substantiallyrectangular cross-sectional shape (down to a film-like thickness of e.g. 0.5 mm or less) etc. It may also be provided, that the passagewaycomprises more than one constriction in a sequential arrangement alongits longitudinal axis. Furthermore a combination of various sealinglips, surfaces, or arrangements may be provided.

In the preferred embodiment of FIG. 1, surface 19 at the first end 11 ofplunger 10 is angled backwardly towards the passageway 13. In use,plunger 10 is inserted into a cartridge such that surface 19 at thefirst end 11 of plunger 10 faces the material contained in thecartridge. In the embodiment shown in FIG. 1, the backwardly-angledsurface 19 terminates at the constriction 14 so that thebackwardly-angled surface 19 and the constriction 14 form an overallsurface facing the material that is progressively recessed towards thepassageway 13. As will be described in more detail below, air that ispresent in the container can thus be easily forced into the passagewaywhile the plunger is inserted so that substantially no air is trapped inthe container once it is closed by plunger 10 and plug 20.

The first end 11 of plunger 10 is also preferably formed as a secondsealing lip 16 for sealing against an outside wall, for example of thecontainer. As shown in FIG. 1, the outer diameter of the plunger 10increases towards the edge of the plunger 10 at the first end 11.

FIG. 2 shows an alternative embodiment of the plunger of the invention.Plunger 10′ shown in FIG. 2 also comprises a first end 11′, an oppositesecond end 12′, and a passageway 13′ extending therethrough. However, incontrast to the embodiment shown in FIG. 1, plunger 10′ shown in FIG. 2comprises a constriction 14′ that is arranged in the passageway 13′ butpositioned towards the back end 12′ of the passageway 13′, i.e. spacedfrom the area of the plunger 10′ where the first end surface 19′ of theplunger 10′ is angled backwardly towards the passageway 13′.

In the embodiment shown in FIG. 2, the constriction 14′ is also formedsuch that an edge 15′ is formed. Moreover, the outer diameter of plunger10′ increases towards the first end 11′ so that a second sealing lip 16′is formed.

A plunger assembly according to the invention is shown in FIG. 3. FIG. 3shows plunger assembly 30 comprising a plunger 10 according to theembodiment shown in FIG. 1. However, the plunger assembly 30 is notlimited to a plunger 10 according to this embodiment. Other plungerdesigns such as the embodiment shown in FIG. 2 are also encompassed bythe present invention. Plunger assembly 30 also comprises a plug 20.Plug 20 comprises a first end 24 and a second end 22. Preferably, aflange 21 is provided at second end 22. Plunger 10 shown in FIG. 3 isidentical to plunger 10 shown in FIG. 1 so that a detailed descriptionof plunger 10 is omitted.

As can be seen in FIG. 3, the diameter d of the constriction 14 ispreferably smaller than the diameter A of the plug 20 at least on thearea were the constriction 14 seals with the plug 20. The seal betweenconstriction 14 and plug 20 is shown in more detail in FIGS. 5A-5D. Theratio of the diameter d of the constriction relative to the diameter Aof the plug is smaller than 1, preferably within a range of 0.75 to 0.5.In an exemplary embodiment the constriction has a diameter of 1.5 mm andthe plug has a diameter of 2.15 mm. These sizes and ratios can depend onthe materials from which the various components are made, especiallyfrom which the plunger is made. In the exemplary embodiment the plungeris made out of polypropylene. If more rigid materials (e. g. polyamide,polyoxymethylene) are used the ratio d to A will be closer to 1 relativeto the exemplary embodiment. Preferably the plugs are made out ofpolypropylene or of a more rigid material like e.g. polycarbonate,polybutyleneterephtalate, wherein the ratio d to A preferably is similaror equal for the different materials.

It is also preferred in the embodiment shown in FIG. 3 that the diameterD of the passageway 13 is larger than the largest diameter A of the plug20, in at least one location other than at the constriction 14. The term“largest diameter of the plug” does not include the diameter of apreferred flange 21, as clearly shown in FIG. 3. The ratio of thediameter d of the constriction relative to the diameter D of thepassageway is smaller than 1, preferably within a range of 0.75 to 0.5.In an exemplary embodiment the constriction has a diameter of 1.5 mm andthe passageway has a diameter of 2.5 mm.

FIG. 4 shows a system 50 for storing a substance according to theinvention. System 50 comprises a container 40, a plunger 10, and a plug20. Container 40 is a receptacle having a compartment 41 for storing asubstance 42. Container 40 furthermore comprises an opening 44 intowhich plunger 10 can be inserted. Although not shown in FIG. 4,container 40 may also comprise a dispensing opening for dispensing thesubstance. Preferably, such dispensing opening is located in thecontainer wall opposite opening 44.

Plunger 10 of the invention can be inserted into and moved in thecontainer compartment 41. Once plunger 10 is inserted into the containercompartment 41, the second sealing lip 16 of plunger 10 abuts againstthe inner wall 43 of the container compartment 41 so that a seal isestablished between second sealing lip 16 and container 40. If no secondsealing lip 16 is provided, the outer diameter of plunger 10 preferablycorresponds to the compartment diameter so that the plunger wall sealsagainst the compartment wall 43.

Furthermore, plug 20 can be inserted into the passageway 13 of plunger10, as described in more detail below with reference to FIGS. 5A-5D.

FIGS. 5A-5D show a sequence of four pictures A through D. In FIGS.5A-5D, reference numerals have been essentially omitted in order toclearly show the components of the storing system of the invention.However, since the components of the storing system shown in FIGS. 5A-5Dare identical to the components shown in FIG. 4, the reference numeralsof FIG. 4 will be used for the following explanation of FIGS. 5A-5D.

The components of the storing system of the invention shown in FIG. 5Aare identical to the components shown in FIG. 4. However, in contrast toFIG. 4, in FIG. 5A, plunger 10 is already inserted into the containercompartment 41 but has not yet reached substance 42.

FIG. 5B shows plunger 10 advanced to its desired position within thecontainer compartment 41. The two arrows shown in FIG. 5B indicate thatthe plunger has been advanced to this position in comparison to FIG. 5A.It can be seen in FIG. 5B that a small amount of the substance 42 storedin the container has been displaced across the constriction 14 into thepassageway 13 of the plunger 10.

FIG. 5C shows the plug 20 being inserted into the passageway 13 of theplunger 10. The plug 20 has been pushed to a position where its frontend 24 already contacts the sealing lip 14. FIG. 5C clearly shows thatsealing lip 14 is already slightly deflected by the plug 20 towards theinterior of the container.

It is also shown in FIG. 5C that the diameter A of the plug 20 issmaller than the diameter D of the passageway 13 of the plunger 10 sothat a space 17 (see FIG. 5D) is formed between the wall of thepassageway 13 and plug 20. Excess material is stored in space 17.

In FIG. 5C, the compartment is fully closed by the plunger 10 and plug20. Upon further movement of the plug 20 into the plunger 10, theplunger 10 is pushed back, which is shown in FIG. 5D by the two blackarrows pointing upwards. Plunger 10 is pushed back by the pressure whichbuilds up within the material stored in the container 40 because thematerial 42 is substantially incompressible. If the plug 20 comprises aflange 21 at its back end 22, the plug 20 is preferably pushed into theplunger 10 until the second end 12 of the plunger 10 has reached theflange 21 of the plug 20 so that the upper end of the space 17 betweenthe plug 20 and the plunger 10 is closed by the flange 21 (see FIG. 5D).Excess substance is thus kept in the space 17.

Although not shown, it is preferred that the plug 20 is pushedcompletely into the plunger 10 and moved back by a short distance inorder to relieve residual pressure. This residual pressure results froma certain elasticity of the container walls and from the fact that abalance will be reached between the pressure building up in thecontainer and friction forces that have to be overcome to move plug 20relative to seal 14 as well as to push plunger 10 back within thecontainer.

As shown in FIG. 8, the plug 20 preferably comprises a steppedconfiguration or indented ring 25 with a smaller diameter into which theconstriction lip 14 fits to lock the plug 20 in place within the plunger10.

It is also clear from FIGS. 5A-5D that air that is present in the spacebetween the first end surface 19 of the plunger 10, and the substance 42contained in the container 40 is allowed to escape through theconstriction 14 and through the vent passageway 13. Due to thebackwardly-angled shape of the surface 19 of the plunger 10, and due tothe angled surface of the constriction 14, any air is forced upwards tothe vent passageway so that almost no air is trapped in the containerwhen excess material flows into the passageway (see FIG. 5B). Initially,the plunger does not have structures allowing air to be trapped when theplunger is pushed into the substance because the sealing lip isundeflected. However, the sealing lip forms an improved seal after theplug is inserted. The material in the container is completely sealed dueto the seal between sealing lip 14 and plug 20, and due to the sealbetween second sealing lip 16 and the container wall.

Since the sealing lip 14 is oriented towards the material (see FIG. 5D),the sealing effect will even increase when the pressure in the materialincreases, for example, when material is pressed forward by the plungerand plug and dispensed through a dispensing opening (not shown). Thetaper providing the second sealing lip also increases the seal effectwhen the pressure on the lip increases. An additional seal effect aswell as a lock of the plug in the plunger are provided by the indentedring 25 (see FIG. 8). Due to the step in diameter, the plug is lockedagainst the constriction 14 so that continued pressure of the plunger 10forward does not cause the substance to force the plug backward and outof sealing engagement with the constriction 14.

FIG. 6 shows an alternative embodiment of the storing system of theinvention. In the embodiments shown in FIG. 6, the container 40comprises a first compartment 41 a for a first substance 42 a, and asecond compartment 41 b for a second substance 42 b. A first plunger 10a is provided for the first compartment 41 a, and a second plunger 10 bis provided for the second compartment 41 b. In the preferred embodimentshown in FIG. 6, the two plungers 10 a and 10 b are connected to eachother by a connecting bar 18. Preferably, the two plungers 10 a and 10 bare integrally formed as one piece.

A first plug 20 a and a second plug 20 b are provided for sealing thecompartments. The two plugs 20 a and 20 b are preferably connected by aconnecting bar 23. Preferably, a retention element 26 (shown in FIG. 9)is provided at the connecting bar 23. Retention element 26 engages witha corresponding recess 19 at the back end of the walls of plungers 10 a,10 b. Once engagement is established, the relative position betweenplugs 20 a, 20 b and plungers 10 a, 10 b is substantially fixed.

FIGS. 7A-7D show how two different substances can be sealed in the twocompartments of the storing system of FIG. 6. Since the components shownin the four pictures of FIGS. 7A-7D are identical to the componentsshown in FIG. 6, reference numerals are omitted in FIGS. 7A-7D forclarity.

FIG. 7A shows the components of the storing system of this embodiment ofthe invention in their initial position. FIG. 7A is identical to FIG. 6.As can be seen in FIG. 7A, the two compartments are filled with thesubstances to different fill levels.

In FIG. 7B, the plungers have already been advanced to their desiredposition. Due to the different fill levels in the differentcompartments, different amounts of excess substance have passed theconstriction and are now contained in the passageway of each plunger. Inthe next step, the two plugs are inserted into the passageways untilthey reach and deflect the sealing lips to form a seal (FIG. 7C). Theexcess substance contained in the passageway of each plunger is storedin the space between the plug and the plunger wall. In the final step(see FIG. 7D), the plungers are pushed further into the compartments sothat the substantially incompressible material lifts the plungers untilthe connecting bar of the plunger contacts the connection bar of theplugs.

Although not shown, it is preferred that the plugs are pushed completelyinto the plungers and then moved back by a short distance in order torelieve residual pressure. This residual pressure results from a certainelasticity of the container walls and from the fact that a balance willbe reached between the pressure building up in the container andfriction forces that have to be overcome to move plugs relative to sealsas well as to push the plungers back within the container compartments.

The embodiment of the storing system shown in FIGS. 6 and 7 isadvantageous because it compensates for imprecise fill tolerances anddifferent fill levels in the container compartments. This is beneficialbecause it is very difficult to fill two compartments with preciselyequal amounts or equal fill levels of material.

This is especially advantageous if the invention is used in combinationwith a delivery system having two or more compartments filled withcomponents that are mixed together when the system is used (e. g. whenthe substances stored in the compartments are expelled through a singledispensing opening by displacing the plunger assembly). In this case thefilling volumes of the individual components have to be within apredefined ratio relative to each other (e. g. 1:1, 2:1, 3:1 etc).

If a dual plunger arrangement is used (as in FIGS. 6 and 7), theplungers are simultaneously advanced towards the substance until bothcompartments are substantially free of air (in the manner describedabove, and also as shown in FIG. 7B). The dual plug arrangement ispushed into the passageways of the plunger arrangement, thus sealing thecompartment (FIGS. 7C and 7D). As it can be seen in FIG. 7D, the ratioof the filling volume of the individual components is defined by thegeometry of the delivery system rather than the filling system.

In an alternative embodiment to the storing system shown in FIGS. 6 and7 the plungers are of a different length, different diameters, or theplungers (not connected to each other) are inserted to differentpositions within the compartment. This is advantageous if the storingsystem is used for providing components in unequal proportion for mixingafter the components have been completely expelled from the deliverysystem. Thus, the invention includes a system having materials in twocompartments wherein there are substantially different amounts ofmaterial in the two compartments, for example ratios of fromapproximately 1:2 to approximately 1:10.

FIG. 10 shows a system for storing a substance according to a furtheralternative embodiment of the invention. The system of the embodiment ofFIG. 10 also comprises two compartments for storing two materials. Inthis embodiment, these two compartments are arranged concentricallywithin container 400. Reference numeral 411 denotes the innercompartment which is surrounded by annular compartment 410.

In the same way, plunger 100 comprises an inner plunger portion 102 aswell as an annular outer plunger portion 101. Both plunger portions 101,102 are arranged concentrically. Outer plunger portion 101 issubstantially cylindrical and comprises at its inner surface a sealinglip 140. The inner plunger portion 102 is substantially inverse U-shapedand substantially annular. At its outer surface, a sealing lip 141 isprovided. Sealing lips 140 and 141 from a first constriction associatedwith the outer compartment 410. The inner surface of annular plungerportion 102 comprises a constriction 142 associated with the innercompartment 411. Apart from the concentric arrangement, plunger 100 andthe provided constrictions are arranged and dimensioned as describedabove with reference to the other embodiments of the present invention.

Plug 200 comprises an inner plug portion 201 and an outer annular plugportion 202. Both plug portions 201, 202 are concentrically arranged.The annular outer plug portion 202 and the inner cylindrical plugportion 201 are connected by connecting plate or disk 230. As shown inFIG. 10, the constrictions of the plunger seal against the plug portionsextending through the plunger passageways.

Plunger 100 is preferably integrally formed as one part, wherein theplunger portions 101, 102 are connected preferably by spokes at theirback end. In the area of the spokes of plunger 100 the connecting disk230 of plug 200 is recessed so that both parts engage with one anotherwhen assembled with each other (not shown).

An exemplary container 80 having two compartments and a dispensingcannula 81 is shown in FIGS. 11 and 12. The plunger 82 and plug 83assembly according to the present invention is also shown in these Figs.Similar containers for use with the system of the present invention areshown in WO 2005/016783.

FIGS. 13A and 13B show a plunger assembly according to a furtherembodiment of the present invention. A seal 14″ is provided as separatepart and assembled into the passageway 13″ of the plunger 10″. Seal 14″preferably has a triangular cross-sectional shape (not shown) or acircular cross-sectional shape (o-ring). The passageway 13″ of thisembodiment preferably (but not necessarily) has a stepped configuration,which means that the passageway has a first diameter D1 towards thefront end of the plunger 10″ and a second diameter D2 towards the backend of the plunger 10″, wherein the first diameter D1 is smaller thenthe second diameter D2. The seal 14″ is received in the second diameterD2 and abuts at the step 95 between the first and second diameter D1,D2, thus being fixed against displacement when the plug 20″ is insertedin the passageway 13″.

In FIG. 13A the plug 20″ is still not completely inserted into thepassageway 13″ of the plunger 10″. FIG. 13B shows the plunger assemblyof this embodiment of the invention after the plug 20″ has been insertedin the passageway 13″. In this stage the plug 20″ seals with the plunger10″ by compressing the seal 14″ between the wall of the passageway withthe diameter D2 and the plug 24′. Preferably, plug 20″ comprises acircumferential flange 28″ for pressing the seal against the step 95.

FIGS. 14A and 14B show a plunger assembly according to a furtherembodiment of the invention. A seal 14′″ is provided at the front end ofthe plug 20′″. The seal 14′″ is preferably of a triangularcross-sectional shape and preferably deformable, thus forming a flexiblesealing lip. Preferably the diameter A′″ of the sealing lip 14′″ issubstantially larger than the diameter D″ of the passageway 13′″. Theplug 20′″ is preferably pre-assembled with the plunger 10′″ in a mannerthat the back end of the plug 20′″ is located in the passageway 13′″ ofthe plunger 10′″ and the sealing lip 14′″ is located outside of thepassageway 13′″. Preferably the sealing lip 14′″ is located within theinwardly tapered area 19′″ at the front end of the plunger 10′″, whereinthe sealing lip 14′″ does not touch the plunger 10′″, providing that theplug 20′″ does not seal with the plunger 10′″ at this stage (shown inFIG. 14A).

FIG. 14B shows the plunger assembly according to this embodiment of theinvention in a stage where the plug 20′″ has been pulled back towardsthe back end of the plunger 10′″, and the sealing lip 14′″ has movedinto the passageway 13′″. In this stage the plug 20′″ seals with theplunger 10″. Because of the larger diameter A′″ of the sealing lip 14′″and since the sealing lip is deformable, the sealing lip 14′″ hasdeflected towards a direction of the front end of the plunger 11′″ upondisplacement into the passageway.

The present invention has now been described with reference to severalembodiments thereof. The foregoing detailed description has been givenfor clarity of understanding only. No unnecessary limitations are to beunderstood therefrom. Many changes can be made in the embodimentsdescribed without departing from the scope of the invention. Thus, thescope of the present invention should not be limited to the exactdetails and structures described herein, but rather by the structuresdescribed by the language of the claims and the equivalents of thosestructures.

The invention claimed is:
 1. A method, comprising: i) providing acontainer having a first inner wall defining a first compartment and asecond inner wall defining a second compartment; ii) filling the firstcompartment with a first substance; iii) filling the second compartmentwith a second substance, wherein the second substance is different fromthe first substance; iv) placing a first plunger in the firstcompartment, the first plunger having a first end, an opposite secondend and a first wall defining a first passageway extending between thefirst and second ends, wherein the first passageway comprises adeformable first sealing lip projecting into the first passageway andwherein a first end edge of the first plunger provides a second sealinglip that forms a seal with the first inner wall of the first compartmentdefining the first compartment after placing the first plunger in thefirst compartment; v) placing a second plunger in the secondcompartment, the second plunger having a first end, an opposite secondend and a second wall defining a second passageway extending between thefirst and second ends, wherein the second passageway comprises adeformable first sealing lip projecting into the second passageway andwherein a first end edge of the second plunger provides a second sealinglip that forms a seal with the second inner wall of the secondcompartment defining the second compartment after placing the secondplunger in the second compartment; vi) connecting with a firstconnecting bar the second end of the first plunger to the second end ofthe second plunger and simultaneously advancing the first plunger towardthe first substance and the second plunger at the same rate towards thesecond substance until the first substance passes the first sealing lipof the first plunger and the second substance passes the first sealinglip of the second plunger; vii) connecting with a second connecting bara second end of a first plug and a second end of a second plug; andviii) pushing the second connecting bar to move a first end of the firstplug into the first passageway of the first plunger until the firstsealing lip of the first plunger is sealed against the first end of thefirst plug and a first end of a second plug moves into the secondpassageway of the second plunger until the first sealing lip of thesecond plunger is sealed against the first end of the second plug. 2.The method of claim 1, including fixedly connecting the first connectingbar to the second connecting bar.
 3. The method of claim 1, whereinduring step vii) the first substance passing the first sealing lip ofthe first plunger is received in a space between a first inner wall ofthe first passageway of the first plunger and the first plug.
 4. Themethod of claim 1, wherein during step viii) the second substancepassing the first sealing lip of the second plunger is received in aspace between a second inner wall of the second passageway of the secondplunger and the second plug.
 5. The method of claim 1, including fillingthe second compartment with a different volume of the second substanceas compared to a volume of the first substance in the first compartment.6. The method of claim 1, including moving the first plug relative tothe first plunger while the first sealing lip is still sealed againstthe first plug, and moving the second plug relative to the secondplunger while the first sealing lip is still sealed against the secondplug to move both the first end of the first plug and the first end ofthe second plug at an identical rate away from both the second end ofthe first plunger and the second end of second plunger.